Field of the Invention
The present invention relates to a mobile communication system and, in particular, to a method and apparatus for performing contention-based access in a mobile communication system.
Description of the Related Art
Mobile communication systems have developed to provide the subscribers with voice communication services on the move. With the advance of technologies, the mobile communications have been evolved to support high speed data communication services as well as the standard voice communication services.
Recently, as one of the next generation mobile communication system, Long Term Evolution (LTE) is on the standardization by the 3rd Generation Partnership Project (3GPP). LTE is a technology designed to provide high speed packet-based communication of up to 100 Mbps and aimed at commercial deployment around 2010 timeframe. As the LTE standard is on the verge of ratification, discussion is focused on LTE-advanced (LTE-A) with the adoption of various novel techniques to LTE. One of these novel techniques is the contention-based access.
Typically, since uplink transmission is performed through the dedicated resource allocated by a base station, collision does not take place in uplink transmission. In order to allocate transmission resource dedicatedly, however, the terminal has to request the base station for transmission resource allocation, resulting in increase of transmission delay. In order to overcome this problem, the base station may use a part of the transmission resource as contention-based access resource. The transmission resource known as contention-based access resource is freely used by the terminals having data to transmit. In uplink transmission using the contention-based transmission resource, collision is inevitably due to transmission attempts of a plurality of terminals. Since the contention-based transmission has low transmission reliability, it may cause significant side effect to allow the contention-based transmission for all the types of data without restriction.